Washington cops found the makings of a firebomb in a raid on the headquarters of world-finance protesters yesterday – hours before some 600 demonstrators were arrested near the White House for lacking a permit.

The arrests and the raid were seen as a pre-emptive strike by authorities hoping to avoid a repeat of the violent protests outside a December World Trade Organization meeting in Seattle – but demonstrators charged that cops were trying to provoke them and denied plotting violence.

“There is nothing in that building that can be considered dangerous,” protester Nadine Block said. “If the police find something there, it could be because they put it there.”

Authorities also ruled that the raided headquarters – an abandoned row house taken over by protesters – was “unsafe” and kicked out hundreds of demonstrators who had planned protests today and tomorrow.

Among items seized in the raid was a plastic container with a rag stuffed inside and a wick that “looks like a Molotov cocktail,” Assistant Police Chief Terry Gainer said.

Officials said the building was a fire hazard, with a jury-rigged electrical system, chained doors and a propane stove that was not up to code.

Only 12 hours earlier, an undisclosed amount of ammunition and firebomb instructions were found in another raid on the house.

“We lost our food, and our cooking supplies, and we’ve got thousands of people to feed,” said organizer Antonia Jahasz, 29.

“With one of the highest homicide rates in the country, D.C.’s finest are guarding our dangerous puppets,” she said, referring to puppets, signs and banners also seized.

Police Chief Charles Ramsey said he expected 10,000 or more protesters at the height of the demonstrations.

Shortly before cops shut the demonstrators’ headquarters, 20 protesters from 10 countries marched on the home of World Bank President James Wolfensohn to deliver a letter ripping the institution’s lending policies and demanding an international boycott of the bonds that are the main financing source for the World Bank.